Researchers at the Massachusetts Institute of Technology (MIT), United States, have created sensors comprised of carbon nanotubes coated with protein fragments found in bee venom that are so sensitive they can pick up a single molecule of an explosive such as TNT. The new sensors, if developed into commercial devices, would be far more sensitive than existing explosives detectors, such as those used at airports. The sensor takes advantage of carbon nanotubes’ natural fluorescence, by changing the fluorescent light’s wavelength, instead of its intensity, when the target binds to the bee-venom proteins coating the nanotubes. A new type of microscope can detect the change in wavelength. By coating several different nanotubes in different bombolitins – the bee venom proteins – the researchers can identify a unique “fingerprint” for each explosive they might want to detect. According to Michael Strano, an associate professor of chemical engineering, “Compounds such as TNT decompose in the environment, creating other molecule types, and those derivatives could also be identified with this type of sensor. Because molecules in the environment are constantly changing into other chemicals, we need sensor platforms that can detect the entire network and classes of chemicals, instead of just one type.” The sensor needs to be coupled with a commercially available concentrator that would bring molecules floating in the air in contact with the carbon nanotubes before it can be practical for widespread use. “It doesn’t mean that we are ready to put these onto a subway and detect explosives immediately. But it does mean that now the sensor itself is no longer the bottleneck,” Strano says. “If there’s one molecule in a sample, and if you can get it to the sensor, you can now detect and quantify it.”
http://web.mit.edu/newsoffice/2011/explosive-detection-0510.html